A Small, Signel Block Laser Coherence Discriminator

The problem of low-power CW laser detection in not detector sensitivity but detector selectivity. the only reliable laser feature that is not modified by propagation through the atmosphere is its temporal coherence. Based on this, Physical Optics Corporation (POC) proposes to develop and fabricate a new type of coherence discriminator that is capable of detecting the presence of low-power laser illumination against a background of much brighter natural and man-made incoherent light sources. This is achievable because only temporally coherent radiation will be modulated and consequently, synchronously demodulated by the proposed coherence discriminator. The proposed device would be usable in all spectral bands of interest. The sensor itself is expected to be rugged, small (<= 8 inches 3), lightweight (<= 200 grams), and inexpensive to fabricate. Thus, a proliferation of devices could be placed on the surfaces of tactical platforms, and eventually, the device concept could be incorporated into "smart skin" designs. In Phase I of this program, a breadboard model of the proposed laser discriminator for the IR spectral region will be built, and its high discrimination capability will be proved experimentally. In Phase II, two field testable prototypes will be fabricated.